1. Field of the Invention
The present invention generally relates to water detection systems associated with the drain pan placed under the air handling unit of an air conditioning system or associated with the drain line connected to the weep hole of the air handling unit, and more particularly relates to a fluid-sensing switch system that monitors a pre-established threshold fluid level in the primary drain pan inside an air conditioning unit or other condensate-producing unit, and also monitors a typically different pre-established threshold fluid level in a secondary drain pan positioned under the unit, providing redundant safety response capability. Instead, prior art systems monitor the fluid level in the drain line carrying water or other fluid away from the unit's weep hole or monitor the fluid level in the secondary drain pan, but do not monitor the fluid level in the primary drain pan inside the air conditioning unit or other condensate-producing unit. Once the threaded plug of a sensing probe in the present invention is connected to the unit's weep hole, it positions a center sensor extending through its false-trigger-reducing resilient piece in a position to wait for fluid rising over a dam, without prematurely causing any activation as a result of water collected behind the dam. The resilient piece has opposing ends and a cone associated with each opposing end, one of which provides a drip path to wick fluid away from the center sensor. The center sensor provides a first power potential, while a circular sensor also present provides the second power potential needed for safety-related signal generation, with the second power potential being a neutral potential. A signal-generating member connected to both sensors is electrically connected to the fluid-producing unit to shut it off, and/or to a pump for its activation to remove fluid from the secondary drain pan. The signal-generating member is also placed in association with the secondary drain pan to monitor a pre-established threshold fluid level therein. Mounting of the signal-generating member to a vertically-extending wall of the secondary drain pan is preferably accomplished via double-sided tape and/or fasteners.
2. Description of the Related Art
Air handling systems such as furnaces or other heating, ventilating, or air conditioning systems associated with a building structure typically have a drain pan underneath at least portions of the air handling unit to catch collected condensation and prevent damage that would otherwise result from fluid overflow. Such damage can be to the unit itself, and/or its surroundings. However, the condensation produced in a twenty-four hour period can be more than the drain pan can hold. This is a particularly common occurrence with some air conditioning systems. Therefore, the drain pans thereof are often mounted in a non-level orientation and connected to a drain pipe or hose that carries the collected condensate to a suitable location outside the structure. However, in some fluid collection applications the removal of condensate from a secondary drain pan requires pumping. Typically when a secondary drain pan is used, a fluid level sensing unit is placed in association with it. Thereafter, when the depth of collected condensate reaches a predetermined threshold level, the fluid level sensing unit generates a signal and sends it to a fluid-sensing switch systeming circuit to activate the pump. When sufficient water is removed from the drain pan for the water sensor to stop sending the activation signal, the fluid-sensing switch systeming circuit deactivates the pump. In this manner, the pump is only activated when necessary to pump water out of the drain pan, thereby prolonging the life of the pump, while preventing water from overflowing the vertically-extending walls of the drain pan.
Many prior art fluid level sensors in current use contain an upwardly-deployable float body. One disadvantage thereof is that during installation time-consuming float body height adjustment is typically needed to make certain that fluid collected in the associated secondary drain pan does not flow over the pan's vertically-extending walls, taking into consideration that condensate production does not immediately cease when the fluid-producing unit is shut off. The float body also requires a level orientation for proper and reproducible operation. If a float sensor is not correctly oriented, its float body may not immediately deploy and the pump may not be activated in time before fluid overflows the drain pan's vertically-extending walls. Such overflow generally leads to damage in the area around the secondary drain pan, which may involve a floor, walls, a ceiling, and/or fixtures associated therewith, as well as other items located nearby. In addition, false signaling may occur that causes pump activation when insufficient water is present, thereby damaging the pump. Thus, what is needed to provide a solution for all of the disadvantages noted above in the prior art, is a fluid level sensing unit for a collection/drain pan used with condensates or other fluids, which is durable for long-lasting and predictable use, has a reduced sensitivity to false signaling, does not require undue effort for accurate orientation, and can be relied upon to produce a signal after only a small amount fluid collects in the pan. These are all features provided by the present invention. Other desirable features and characteristics of the present invention will become apparent from the following invention description and its appended claims, as well as the accompanying drawings.